c: Propagate erroneous types to declaration specifiers [PR107805]

c: Propagate erroneous types to declaration specifiers [PR107805]

Without this change, finish_declspecs cannot tell that whether there
was an erroneous type specified, or no type at all.  This may result
in additional diagnostics for implicit ints, or missing diagnostics
for multiple types.

	PR c/107805

gcc/c/
	* c-decl.cc (declspecs_add_type): Propagate error_mark_bode
	from type to specs.

gcc/testsuite/
	* gcc.dg/pr107805-1.c: New test.
	* gcc.dg/pr107805-2.c: Likewise.